【Size】 Diameter 1/2 inch = 12.7mm, precision G200, Package includes 30 pieces brass ball. 【Material】Made by High Precision Brass (H62), have the ability to resist the corrosive effects of fuel oil, gasoline, dry carbon dioxide, benzene, lime-sulphur mixture and similar chemical agents. 【Smooth surface】 Fine grinding to ensure that each brass ball is uniform in size. The surface of the steel ball is very smooth,easy to shape without cracks. 【Features】The Brass ball has high precision and small tolerance, suitable for many occasions and different precision requirements. 【Application】used in a wide variety of applications including special valves, industrial pumps, electronic devices, safety switches, heating units, casters, drawer slides, door locks, furniture rails.